This invention relates to a rotary type information retrieving machine, in which a multitude of information-containing cards are arranged in a designated sequence around a rotational body such as a cylindrical drum with one side of each information card being pivotally fitted thereon, and the rotational body is rotated in a definite direction to display the information-containing surfaces of the cards as selected in a viewing window of the retrieving machine.
This kind of device is provided with selection switches equal in number to the information cards, by the selection of which any one of the information cards is brought to the viewing window. Therefore, the selection key, the selection switch associated with the selection key, and the information card exactly correspond to each other in number.
However, with increase in the amount of information to be stored in the information cards, it becomes difficult to accommodate all the information cards as desired in a very limited space of the retrieving machine, maintaining the above-mentioned one-to-one relationship between the card and the selection key. Accordingly, it is necessary to cause a plurality of such information cards to be changed with a single selection key so that a greater number of cards may be accommodated in the retrieving machine.